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Date:   Thu, 27 Oct 2022 18:05:48 +0800
From:   Zhao Liu <zhao1.liu@linux.intel.com>
To:     Wei Liu <wei.liu@kernel.org>
Cc:     "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        =?iso-8859-1?Q?Dexuan=A0Cui?= <decui@microsoft.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, linux-hyperv@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        =?iso-8859-1?Q?Ira=A0Weiny=A0?= <ira.weiny@intel.com>,
        "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        Zhenyu Wang <zhenyu.z.wang@intel.com>,
        Zhao Liu <zhao1.liu@intel.com>
Subject: Re: [PATCH v2] x86/hyperv: Remove BUG_ON() for kmap_local_page()
Message-ID: <Y1pX/BGRgceJcEE9@liuzhao-OptiPlex-7080>
References: <20221020083820.2341088-1-zhao1.liu@linux.intel.com>
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On Wed, Oct 26, 2022 at 03:17:18PM +0000, Wei Liu wrote:
> Date: Wed, 26 Oct 2022 15:17:18 +0000
> From: Wei Liu <wei.liu@kernel.org>
> Subject: Re: [PATCH v2] x86/hyperv: Remove BUG_ON() for kmap_local_page()
> 
> On Thu, Oct 20, 2022 at 04:38:20PM +0800, Zhao Liu wrote:
> > From: Zhao Liu <zhao1.liu@intel.com>
> > 
> > The commit 154fb14df7a3c ("x86/hyperv: Replace kmap() with
> > kmap_local_page()") keeps the BUG_ON() to check if kmap_local_page()
> > fails.
> > 
> > But in fact, kmap_local_page() always returns a valid kernel address
> > and won't return NULL here. It will BUG on its own if it fails. [1]
> > 
> > So directly use memcpy_to_page() which creates local mapping to copy.
> > 
> > [1]: https://lore.kernel.org/lkml/YztFEyUA48et0yTt@iweiny-mobl/
> > 
> > Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> > Suggested-by: Ira Weiny <ira.weiny@intel.com>
> > Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> 
> Applied to hyperv-fixes. Thanks.

Sorry Wei, I appology for not deleting unused variables, which caused
the next tree break. Do I need to send another v3 to make up for my
carelessness?

Zhao